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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fde0829b634aff3539bbe3989e9ebe2934a6856d7593a2c2a5a22e81e87d04b0' 
  AND token = 'ZZ2RAoWoo7DaOTvA9FYYsY1dTWxr5KrzsaG4jbXn+hA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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