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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdd35c0a6f20f0c49972b050bbd9dfc37fb4ed1d3131ee7316cd1d3d51220f9c' 
  AND token = 'DxWuKkwmQH4eroFr99IF7ApeDXcvVsGDDji06Kgg7Sg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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