SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0e978790051efdf3800696d384859614e65b0772ded3849b7db6d7d41bff396' 
  AND token = 'gSan/Psi45Fc1unQeaZop550Jx/Swij1m0QPJDOm9Qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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