SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b70bbcd43d3178b223569af72d6d1f3f15b33a1b17a39d8f33825774365ee4c' 
  AND token = 'sfoIVtpvyvWcEZkmidNKL4AJWbjngmMXHyFEuwyeoLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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