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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6a178aefa30a4979bf9f9f112e9f910e094c45ac6b63efc5f89d158575c37c3' 
  AND token = 'KaiGnkyv2rKWdaTSfQ0UY+74Gpf9TQUY7+9fe0/5SBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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