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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b902df0b51a58c2e91ef4d24554e5f59ccf513e691ee5decc0e5d862ab373c' 
  AND token = 'Xrk5vs7mNlPWuVHLu0haIasVDzVE3nYJ1n3XbZSpDH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}