SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dbada8e3595f914b40675084e5de2f4424daabae71d30e60c979e534db8b706' 
  AND token = 'rn9Hbi7EDSITJyNDbszFVCIGBpaHkW+PbcHMgI+WNmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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