SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8f4dc1038db430182367ceb2c5e666af0ba04df6369347639bd0b6fdc90cc78' 
  AND token = 'DlTu37NdPd0M03rnkSJuDFd6TNwiapy23r7H/Jxz4TA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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