SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37666bf4f7ab2887fd83aabc47e8781b4113fb7a221c591df6750e67a6fa990a' 
  AND token = 'FG5ieYItFV5wA0SjpfTFus4qud3TOvjCJGsgBiL+Gko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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