SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc80e8ea4f2f0b3c7c53105a6bd4ed4bd886854bdff260721fc4285ac6b3b937' 
  AND token = 'cb/VaMI7oidzIc5qdEuYURbvBF22nys3XCC8S935xH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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