SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e27771127976a0d0b3243a2e20a59de096d26052cc08c3500ea40b16784e142' 
  AND token = 'aePN1n2KYl4evQkLlGJ9CfQnGvmdJNwRQR2L8Um6fYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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