SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd70a20a5ccbaa78e3c46411a135e24476f5aafa61556b25cbeeb03bd3f4a0a73' 
  AND token = 'f0mW8DJ++Ra1aAxL4v91JNS/j3ujAvMG26Y/dRjZajc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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