SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b2e878634fc17efe0490c506c479fd2455d267c57608c3dfef7aa26f8fbe741' 
  AND token = 'jGemWC00lZwG+hrC/rjSVcX6iDVPFWzqRniYpK7HaiE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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