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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8198bec646e68ebde7620d0b92d759b91be0b951ffdf5ee43e05168e56418e3' 
  AND token = 'tjPUiRvt69I0Sh/ya0ddsQgHgvQUf8h2dqRbniTc0Vs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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