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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3cb96ca96d7a00201c7436ec4abfb57dbd1f4494e59794e3a23026b32e5b509' 
  AND token = 'KSTV2MpraoZU9BcxqM+QV5xkjy218nHGzBphtVC90Xo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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