SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd641f81bf02e44210d21f5a149853708580e610c6a9cbbd53e6e75938f02b03' 
  AND token = 'nwpf3aV/p8YQ4fK31AWUlm+iUznhxyiZSbkXNMBvLB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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