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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4a0b0e7ff0e5a0b889910c535a54dee5c307d72f5af982e2bd12e6e607c38f4' 
  AND token = 'xcHAhWXMd93/tW8ATO+RNdC2YzcG0eGFujl8hpR3V8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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