SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f56419285b3b26bf5dd3a3d9cdf8b4cf7f9a166d5501b0c2ac6f2bfcccff5b3c' 
  AND token = 'KHzciGSH+f1BRYDn1EMhRbVH7Kgs7fl81aM1+CL31lc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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