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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc58ca250e60b05bdf2a5d56425d04008db07788591d010e44a97f78d696e266' 
  AND token = '+Wj4jwTakHLthX92oxdYj6SpYY3svqLnRWHmVHl0boo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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