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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9d2ec6f4d4768222cbcc8901ce7521bd4bce6a8a396bb5c9766d0b4d716df69' 
  AND token = 'd4wRL8ezJ16vwKmf+/0pEvXWKnzJvIEWTYgFb/sA0Lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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